1. Field of the Invention
The present invention relates to an apparatus for and a method of correcting a component holding position, and more particularly to an apparatus for and a method of correcting a component holding position in a component mounting apparatus for holding a component with a holder and mounting the component in a predetermined position.
2. Description of the Related Art
In an electronic circuit, electronic components are mounted in predetermined positions on a circuit board on which wiring patterns are formed in advance. Then, the electrical continuities are established between electrodes of those electronic components and the wiring patterns. Accordingly, the predetermined connections are attained.
When the electronic circuit is formed in this way, the components must be mounted in turn on a circuit board made of insulation material, in which predetermined wiring patterns are formed on a surface thereof. Here, a position at which the component is mounted must be a position at which the electrode must be normally connected to a land for the connection of the wiring patterns. If the position at which the component is mounted is deviated or out of alignment, a desired connection is not attained, which may result in an occurrence of an erroneous wiring or a short-circuit trouble.
A mount machine is used in order to automatically mount the circuit components on the insulation board. It is possible to avoid the above-mentioned problems by improving the mount accuracy of this mount machine.
The supply of the components in such an automatically mounting apparatus is carried out in a manner that it is accommodated in a concave portion on a tape to be fed from a component tape feed reel of a part cassette, and the component in the concave portion of the tape located at the position from which the component is taken out is taken out by an suction nozzle, and automatically mounted.
Japanese Laid Open Patent Application (JP-A-Heisei, 7-212095) discloses a component mount method for totaling a deviation amount in an inspection measurement result for each inspection unit of an inspection device at a step of mounting a component on a board, for each inspection unit, and estimating a deviation amount of the board from the totaled deviation amount for each inspection unit, and then estimating the deviation amount of the board or calculating a deviation amount from which the board deviation amount is subtracted for each inspection unit, on the basis of a difference between the estimated deviation amount for each inspection unit caused by the board deviation and the above-mentioned deviation amount for each inspection unit.
In the conventional above-mentioned automatic mounting apparatus, when this mounting apparatus holds a target component, it is treated that this target component is always located in advance at a predetermined position of a concave portion of a tape. However, in association with the reduction and the miniaturization in the dimension of the component to be treated in the component mounting apparatus, when the suction nozzle absorbs the component from a constant position, a trouble is brought about such as an erroneous capturing, a slant holding, a displacement of a holder or the like.
FIG. 12 shows a case where a center of an suction nozzle 2 is deviated with respect to a center of a component 1. If image recognition is tried by a television camera in such condition, this try results in a problem that a shade of the nozzle 2 is erroneously recognized as a shade of the component 1.
Also, if the component 1 is absorbed at an offset state with respect to the center of the suction nozzle 2 as shown in FIG. 13, this results in a problem of a so-called standing suction at which an suction force causes the posture of the component 1 to be changed from a horizontal state to an oblique state. If the component 1 is obliquely absorbed in this way, the component 1 cannot be normally mounted on the circuit board, or the component 1 is fallen from the suction nozzle 2 in the course of the absorbing operation because of the lack of the suction force.
The failure of the suction of the component 1 as shown in FIG. 12 or FIG. 13 directly leads to an occurrence of a defective sample or a drop in productivity. So, such situation must be unlimitedly reduced to zero. Accordingly, the predetermined position of the component 1 needs to be normally held by the suction nozzle 2.
The method of analyzing the deviation of the circuit board and mounting components thereon disclosed in Japanese Laid Open Patent Application (JP-A-Heisei, 7-212095), although firstly trying to set the offset, uses the above-mentioned trial result in its original state after the trial, and does not change the offset in the course of the absorbing operation. Thus, in a case of a sequential mounting of the components, even if the first setting of the offset amount is normally carried out, the disorder of the offset amount during the mounting results in a problem that the normal amount operation is not always carried out. That is, even if the offset amount is normally set, if the offset amount is out of order after that, an suction error is brought about, which results in a problem of an occurrence of a mounting error.
The present invention is proposed in view of the above-mentioned circumstances and is to provide a component mounting apparatus which can solve a trouble caused by a deviation in a position of a component held by a holder, such as an suction nozzle or the like, and accordingly mount a component in position.
An aspect of the present invention relates to a component holding position correcting apparatus in a component mounting apparatus for holding a component with a holder and mounting the component in a predetermined, said correcting apparatus comprising:
a detector for detecting a deviation of a holding position of the holder with respect to a standard position of the component; and
a controller for correcting a holding position at which the holder holds a next component, on the basis of the deviation detected by the detector.
Here, the controller may correct the holding position, on the basis of a value in which the deviation detected by the detector is multiplied by a sensitivity coefficient. And, the standard position of the component is located at a substantial center of a plane held by the holder, or a position deviated by a predetermined direction and length with respect to the center.
Another aspect of the present invention relates to a component holding position correcting apparatus in a component mounting apparatus for holding a component from a component pickup position of a part cassette with an suction nozzle, and mounting the component in a predetermined position on a circuit board, said correcting apparatus comprising:
a detector for detecting a deviation of a holding position of the suction nozzle with respect to a standard position of the component; and
a controller for correcting a holding position at which the suction nozzle holds a next component, on the basis of the deviation detected by the detector.
Here, the detector may be an image recognition camera. And, it may be designed such that the components are accommodated in concave portions for component accommodation, in a one-to-one relation of a tape, and the tape is sequentially fed on the part cassette, and the component located at the component pickup position is held by the suction nozzle.
Thus, according to such an apparatus for correcting a component holding position, the deviation amount of the holding position of the suction nozzle at a previous time can be used to carry out the correction for the holding position at which a next component is held. Thus, the holder can normally hold the next component. The sequential repetition of such operations enables the component to be always normally mounted on the predetermined position on the circuit board. Hence, it is possible to provide the component mounting apparatus having the high accuracy, the high stability and the high reliability.
The invention with regard to a method of correcting a component holding position is a method of correcting a component holding position, characterized in that in a component mounting apparatus for holding a component with a holder and mounting the component in a predetermined position, in which:
a detector detects a deviation of a holding position of the holder with respect to a standard position of the component, and
a controller corrects a holding position at which the holder holds a next component, on the basis of the deviation detected by the detector.
A preferable embodiment in the present invention is designed such that each time a mount head holds a component in turn, a deviation amount of an suction position with respect to a center of the component is recognized by a usual camera for a mount position correction, and its deviation amount is fed back to a movement amount of the mount head when a next component is held. Here, at a time of the feedback, 100% of the deviation amount is not used, and a value obtained by multiplying the deviation amount by a sensitivity coefficient is fed back. Also, when a portion other than the center of the component is held by the holder, the above-mentioned feedback is carried out by considering in advance an offset amount of an suction position with respect to the center of the component.
If the correction operation via such feedback is repeated in turn, after a first component is normally held, a position of an suction head is automatically changed to an optimal position in turn each time a component is held. Not only the optimization of the holding position but also the optimization of the recognition position can be attained by using a mount position correction camera or a correction sensor as a camera for recognizing a holding position. That is, the component holding position of a robot is always stable. This stabilization enables the holding position to be located at the substantial center of the component. Thus, it can be recognized at the best sensitivity of the component recognition camera or sensor.
According to such an embodiment, the mounting apparatus tries to automatically keep the component holding position at the optimal position, which results in the sharp decrease in the erroneous capturing of a component frequently occurring in the conventional technique, namely, the accident of the non-suction of a component. Also, the suction holder automatically maintains its holding position, which results in the sharp decrease in the suction error, such as the erroneous suction of a corner of a component or the lateral suction of a component.
Since the holding position of the component via the holder is always stable, the recognition position of the fixed camera is also stabilized. Accordingly, it is possible to always recognize the component near a center position of the camera, at which a distortion of a lens or the like is little. This contributes to the improvement of the mount accuracy. Moreover, the holding position of the component via the holder is stabilized and located at the substantially center of the component. So, when the component is mounted at a certain angle, a calculation error is not easily brought about. Also, the holding position of the component via the holder is stabilized and located at the substantial center. Thus, it is possible to protect the suction nozzle constituting the holder from being located outside the component, and erroneously recognized as the component at the time of image recognition.
Thus, according to such a method of correcting a component holding position, the deviation amount of the holding position of the component detected by the detector is effectively used. Then, such a deviation amount is used to carry out the correction when the next component is held. Accordingly, the next component is normally held by the holder. Moreover, since this operation is infinitely repeated, the component can be mounted at the high stability and the high reliability.